Roll-to-Roll OLED for LightingMi (M ti ) Y L T D id J S ith Ah t Gü E l tMin (Martin) Yan, Larry Turner, David J. Smith, Ahmet Gün Erlat, Brian Scherer, Ri-an Zhao, Anil Duggal
GE Global Research
AIMCAL Fall Technical ConferenceOctober 21 2009October 21, 2009
What is an OLED?
• Light emission occurs when charges injected from opposite electrodes recombine in organic layer(s).
Tremendo s technolog gro th o er last• Tremendous technology growth over last decade driven by display industry.
• Not an inorganic LED! Amorphous films!
Current technology not roll-to-roll!
2 /GE Global Research
October 21 2009
Current technology not roll to roll!
OLED Offer Novel Features for New ProductsMechanical Flexible Thin and Light TransparentMechanical Flexible Thin and Light Transparent
Color TunableColor Tunable
3 /GE Global Research
October 21 2009
OLED Development Paradigms
“Evaporated” “Solution-Processed”
Organic layers evaporated Organic layers coated orOrganic layers evaporatedin high vacuum
CathodeCathode
Organic layers coated or printed from solution
Cathode
Transparent AnodeTransparent Anode Transparent Anode
• More mature technology.T i ll l (4 20)
• Typically fewer layers (2-3).
Transparent AnodeTransparent Anode p
• Typically more layers (4-20).• Difficult to scale to large area.
• Development cycle is slower.• Potential for much lower cost.
(“S ll l l ” h) (“Polymer” or “Large Molecule”
4 /GE Global Research
October 21 2009
(“Small-molecule” approach) ( Polymer or Large Molecule approach)
GE OLED Vision
“Lighting Wallpaper”
• Energy Efficient• Low Cost• Low Cost• Thin and Flexible
New design possibilities could change the way we think abo t lighting!
5 /GE Global Research
October 21 2009
think about lighting!
R i t A i t C l Hi h CRI C l St bilit L C t
Approaches to Illumination-Quality Light
Independent RGB Elements
Requirements: Appropriate Color High CRI Color Stability Low Cost
Single White Emission LayerSubstrate/ITO
+ Color tunability possible.
Cathode+seal
Organic layers
+ Simple, low cost designs possible.
Down-conversion from Blue
+ Active means for color stability- Extra complexity/cost.
- Materials challenge (single chromophore).- Color stability (multiple chromophores)
Multiple (RGB) Emission Layers
Substrate/ITO
White Light
V
Downconversion Layer
Organic layers
Down conversion from Blue Multiple (RGB) Emission LayersSubstrate/ITO
Organic layers
VCathode+seal
Organic layers
+ Simple, low cost design.+ Inherently color stable.
Cathode+seal
+ Single material set can cover all applications.- Complex device design.
6 /GE Global Research
October 21 2009
- Relies completely on blue OLED - Color stability with life and brightness.
Large Area Devices are Possible
series current pathseries current path
1 element
5 element
12 element
• Distributes current over a large area in spite of resistive electrode.• Device architecture is tolerant to shorting faults.
7 /GE Global Research
October 21 2009APL 82, 2580 (2003)
Roll-to-Roll OLED Fabrication
OLED R2R Line Old Techniques + New Inventions
NIST ATP P (2003 2007)NIST ATP Program (2003-2007)Partner – Energy Conversion DevicesGoal – Prove that continuous roll-to-roll OLED fabrication is possible.Goal Prove that continuous roll to roll OLED fabrication is possible.
OutputModular roll-to-roll line for designed for manufacturing research
8 /GE Global Research
October 21 2009
Modular roll-to-roll line for designed for manufacturing research.
Common early output.
Current output. Low cost, high performance OLED
lighting product
E i i /Advanced device
Engineering / debugging
structure / high performance material / upgraded hardware/ optimized process
10 /GE Global Research
October 21 2009
Roll-to-Roll Manufacturing Choices
W t ti t h i ( )? H ti th d?Wet-coating technique(s)? Hermetic method?Print organics directly? Glass luminaire?
Ultra high barrier coating?Inkjet, gravure, flexographic?
Blanket coating + post-patterning?Ultra-high barrier coating?
As substrate?As encapsulation?As luminaire?
j , g , g p
Laser ablation?M h i l ib ?
Hybrid wet/dry process? All-wet process?
As luminaire?
System integration method? Printable cathode?
Mechanical scribe?
System integration method?
Dry deposition rate/cost?
Atmosphere-vacuum transition?Intermediate roll-up?
Printable cathode?
Lamination?
Dry deposition rate/cost?
• Correct answer changes as device designs/materials evolve.• Research roll to roll line allows ongoing evaluation of alternatives
11 /GE Global Research
October 21 2009
• Research roll-to-roll line allows ongoing evaluation of alternatives.
Unique to OLED Example 1 - SAW“Solvent-Assisted-Wipe” - Mechanical scribe-like technique for organicsSolvent Assisted Wipe Mechanical scribe like technique for organics.
ConceptConcept
Appropriate solvent choice enables …Simultaneous removal of all organic layers without damaging underlying i i ti l ti binorganic coatings on plastic web.
ORSelective removal of specific organic layer.
Roll-to-roll implementation works!
12 /GE Global Research
October 21 2009
The Problem
Unique to OLED Example 2 - UHB
OLEDTransparent electrode
Polymeric substrateH2O O2
Commercial available polymeric substrate
The Solution3,530 hrs at 23°C 40%RH
OLED
Graded ultra high barrier
Transparent electrode
Chem resist layer
High heat polycarbonate
Chem resist layer
GE Ultra-high Barrier (UHB) Substrate
H2O O212 mm
13 /GE Global Research
October 21 2009
Proved that high barrier substrate is possible
Defect-Driven Moisture Permeation
1000 Uncoated
Non-Fickian Diffusion ~ 100 defects/mm2
Defect Imaging w/ Acetone
10
100
100%
O2
20x
~1mm
Defect Imaging w/ Acetone
0.1
1
@ 2
50 @ ~1mm
1 10 100 1000
0.01
0.1
OTR
Detection limit
SiNx Thickness (nm)
14 /GE Global Research
October 21 2009
Barrier performance of single layer inorganic coating is defect limited
Permeation Simulation: Multilayered Barrier
Assumptions: - 2 perfect barriers
Fick’s Law:
C ti it
1
ConductionLi it d
p- each barrier has 1 defect- defects are offset/decoupled
Continuity:
DiffusionEquation:
LimitedRegime
Rat
io
Low
0 1
Flux
R
Flux Ratio =Flux2 Layer System
Flux 1Barrier System
High 0.1 1 10
0.1
Distance/Offset
Offset
DistanceWork in this regime toachieve Ultra-High Barrier
15 /GE Global Research
October 21 2009
GE’s Approach: Graded Ultra-high Barrier (UHB) by Plasma Enhanced Chemical Vapor Deposition (PECVD)
XPS Spectrum of Graded UHBGE’s Graded Ultra High Barrier
InorganicOrganiczone Inorganic zone
Cross-sectional TEM of Graded UHB (made in batch mode)
16 /GE Global Research
October 21 2009
Continuous composition transition
Ultra-high Barrier Performance Test: Ca-test2. Defect Imaging1. Continuous - WVTR
EpoxyCa
B i C ti
Glass
2. Defect Imaging
PolycarbonateBarrier Coating
60C/90%RH
W t
23°C/50RH
CaWater vapor permeation over time
8 mm
17 /GE Global Research
October 21 2009
Roll-to-roll (R2R) UHB Process Development
• Achieved graded structure. • Achieved ultra-high barrier performance (low
10-5 g/m2/day)10 g/m /day). • Good transparency. • Good coating adhesion (5B in ASTM3359 tape
pull test).
80
100
40
60%
T
R2R UHB coatedBare substrate
0
20
350 400 450 500 550 600 650 700 750 800
18 /GE Global Research
October 21 2009
Wavelength (nm)
Energy Dispersive X-ray Spectroscopy (EDS)SiOxNySiOxNy
Graded Structure of R2R UHB
T i i El Mi (TEM)
SiOxNySiOxCy
SiSiOxNySiOxCy
Si
glue
Si substrate
Transmission Electron Microscopy (TEM)
12345
19 /GE Global Research
October 21 2009
Achieved graded coating structure.
Ultra-high Barrier Performance of R2R UHB
Continuous WVTR Ca test
8 inch web
Continuous WVTR Ca test
Defect imaging Ca test.1
2
3
1
2
3
Defect imaging Ca test @ 60°C 90%RH Continuous WVTR Ca test @ 23°C 50%RH
Polycarbonate
EpoxyCa
Barrier Coating
Glass
Polycarbonate
EpoxyCa
Barrier Coating
Glass
• Cell 1: 2.2 × 10-5 g/m2/day. 1
• Cell 2: 1.5 × 10-5 g/m2/day. • Cell 3: 1.7 × 10-5 g/m2/day. • Glass/glass control 1: 7.2 × 10-6 g/m2/day • Glass/glass control 2: 8.4 × 10-6 g/m2/day
2
20 /GE Global Research
October 21 2009
g g y
3
Unique to OLED Example 3 - Lamination
Lamination without vacuum achieves same efficiency asachieves same efficiency as conventionally processed device.
21 /GE Global Research
October 21 2009
…Need better adhesion for large area devices.
APL 88, 223509 (2006)
ConclusionsR ll t ll i /fl ibl l t i i l• Roll-to-roll organic/flexible electronics is real.
• OLED Lighting is getting closer!
Acknowledgements
GE OLED TeamEnergy Conversion Devices
Acknowledgements
Department of EnergyFlexTech Alliance
Energy Conversion Devices
FlexTech AllianceNIST ATP Program
22 /GE Global Research
October 21 2009